ATRIAL-NATRIURETIC-FACTOR RESPONSES TO SUBMAXIMAL AND MAXIMAL EXERCISE

The aim of this study was to evaluate and compare the plasma concentra tion of atrial natriuretic factor (ANF), K+, Na+, blood lactate, heart rate, and blood pressure in moderately trained women. Ten healthy wom en were studied on a cycle ergometer during 20 min of constant submaxi mal and maximal exercise, as well as during recovery. The ANF concentr ation was determined by radioimmunoassay. The results show that, excep t for Na+, all the other variables increased significantly with an inc rease in the duration and intensity of the exercise (P<0.05, P<0.001). In recovery, the values fell (P<0.01, P<0.001). Submaximal and maxima l exercise both cause increases in ANF and this increase is due to the duration and intensity of exercise. However, maximal exercise, rather than submaximal exercise, is the major stimulus for the concentration of plasma ANF. ANF concentration may be a useful test for evaluating the releasing function of ANF in the heart.